The new host of “The Tonight Show” said Monday on Twitter that he would join Emanuel for the frigid swim on Sunday in Lake Michigan. His decision came after Emanuel said he would appear on “The Tonight Show” if Fallon joined him for the event benefiting Special Olympics.

The high temperature on Sunday? Between 16 and 20 degrees in Chicago. The National Weather Service also says there’s a chance of snow.

Still, Fallon tweeted that, “Lake Michigan will have a New York fish this weekend.” Representatives with “The Tonight Show” confirmed he’d participate.